Cooling unit

ABSTRACT

The present invention relates to a cooling unit ( 1 ) comprising a block ( 2 ) having an upper side ( 3 ) and an underside ( 4 ). The block ( 2 ) comprises preferably a porous material and at least one cooling coil ( 5 ) extending at least partially through the block ( 2 ). A media is intended to be cooled in the cooling coil ( 5 ). A part of the cooling coil ( 5 ) is located a maximum of 10 cm, in the vertical direction, from the upper side ( 3 ).

FIELD OF THE INVENTION

The present invention relates to a cooling unit comprising a block having an upper side and an underside, said block preferably comprising porous material, and at least one cooling coil extending at least partially through the block, in which cooling coil a media is intended to be cooled.

BACKGROUND OF THE INVENTION

Evaporative cooling systems are well known and have been developed since at least the 1960s. This type of cooling systems is based on the technique of letting water evaporate from a wet surface. As the water transforms from a liquid state to a gaseous state, large amounts of energy are required. This energy is taken in the form of heat from an adjacent media, i.e. the media which is to be cooled. This media could, e.g., be air or water.

Document WO8701188A reveals an example of such a cooling system, with the cooling unit comprising mainly two channels. The walls are wetted with water in the first channel, and as air passes through the channel, the water evaporates. The energy which is required for performing this is taken from the air which passes through the adjacent, second channel. This results in the air in the second channel being cooled.

One problem with such a cooling unit is that it requires manufacturing of a relatively advanced device provided with channels and made, e.g., of sheet metal, where the channels are alternated such that every other channel contains cooling air and every other channel contains the air to be cooled. Further, the walls of the channel which contains cooling air have to be lined with a material which can absorb water.

In WO01/31272 there is disclosed a cooling device comprising a construction element formed by porous material which can be absorbed and retain water, comprising a plurality of cavities which can be filled with water and a plurality of configurations which form surfaces in contact with environmental air. The water is said to evaporate through said surfaces once they are exposed to air and/or solar radiation. Said construction element has a planar configuration and is susceptible of being placed adjacent to other similar construction elements to cover relatively large areas and forming a heat barrier, including means for interconnecting cavities of similar adjacent construction elements thereby forming a closed assembly of interconnected cavities, and means for connecting said assembly of cavities to a water source. The construction element disclosed in WO01/31272 is intended to be used together with a hose which is arranged in pre-shaped perforations in the construction element.

SUMMARY OF THE INVENTION

It is an object of the present invention to mitigate, or at least reduce, the above problems, and to provide a cooling unit which can be manufactured easily and relatively inexpensively, is intended for out- and indoor use, and is robust as regards external influences.

According to a first aspect of the invention, these objects are achieved by providing a cooling unit comprising a block having an upper side and an underside, and at least one cooling coil extending at least partially through the block, in which cooling coil a media is intended to be cooled, wherein the cooling coil comprises individual portions, each defined as the extension in one direction before a bent of the cooling coil, wherein at least one individual portion of the cooling coil is located a maximum of 10 cm, in the vertical direction, from the upper side, and wherein the inner diameter of the entire cooling coil is in the range of from 3 to 12 mm. The cooling unit or module of the present invention is a unique system where evaporative cooling together with stored energy is utilized very effectively.

The cooling of the media in the at least one cooling coil may be achieved by different means. The first thing to mention is water cooling the block from the outside. As the cooling coil is situated close to the surface of the block, the media flowing in the cooling coil is cooled. Such water on the outside of the block may be mechanically added to the block surface. Moreover, also rain water may moisten the block surface. For instance, when a porous block material is used according to the present invention, such rain water may be enough. The evaporation of the water on the block surface and/or water in the block pores, transfers cooling to the block, which in turn is transferred to the flowing media in the cooling coil. Such evaporation may be driven by solar energy, air heat and/or convection. Also absorbed water vapor on the block surface being evaporated in view of a high vapor pressure in the block material may transfer cooling to the media. As may be noted from above, the heat capacity (thermal capacity) as well as the material structure of the block are of interest for the possible cool transfer. Also the surface structure is of interest as the general concept of the present invention is to arrange the cooling coil near the surface of the block.

As said, the placement of the cooling coil inside of the block is an important aspect of the present invention. For the cooling coil to be able to interact with effects on the surface of the block, such as via e.g. convection, at least a portion of the cooling coil must be placed adjacent the block surface. At least one individual portion of the cooling coil is therefore located a maximum of 10 cm, in the vertical direction, from the upper side. As described in more detail below, preferably more than one individual portion of the cooling coil is located a maximum of 10 cm, in the vertical direction, from the upper side, such as several such individual portions and the bents in between these are located a maximum of 10 cm, in the vertical direction, from the upper side, e.g. within 5 or even 3 cm from the upper side.

Moreover, it is important to understand that several separate cooling coils may be provided within one block, e.g. two individual such coils not being connected to each other.

Furthermore, one other important aspect of the present invention is the diameter of the cooling coil. The diameter, i.e. the inner diameter, must be in the range of from 3 to 12 mm. This is related to be able to obtain reasonable media flows without extreme power inputs. In turn, these flow levels and coil inner diameter range give the possible conversion range of the media within the coil. This conversion range must be held at a reasonable level for the generation of an interesting cooling effect. According to one preferred embodiment of the invention, the inner diameter of the entire cooling coil is in the range of from 4 to 8 mm. In this sense it should be noted that it is natural to use one and the same inner diameter for the entire cooling coil.

In comparison, WO01/31272 does not state anything about the placement of the cooling hose, or the importance thereof. Firstly, a placement near the block surface is not discussed. Moreover, the construction of the hose itself in terms of inter alia inner diameter is not handled. Furthermore, it should also be mentioned that the cooling hose of the construction in WO01/31272 is not a fixed part of the construction thereof.

Also DE19910441 is directed to a block having a tubing or coil. As may be seen in the drawings, the coils are not intended to be placed close to the surface of the block, but instead symmetrically in the middle of the block.

With the device according to the present invention, a simple and durable cooling unit is achieved, which device does not require a supply of energy but operates using the naturally occurring evaporation from the block.

According to one preferred embodiment of the present invention, the block comprises a porous material, such as a material having a porosity of from 20-98%. Such a porous material is preferred as this drives the evaporation and also facilitates a lesser resistance through the material and to the cooling coil.

Also the block size and shape is interest. For the generation of a large amount of cooling effect, the surface size of the block is of interest. An increased surface renders the possibility of larger units and more coil length inside. According to one embodiment of the present invention, the cooling unit has a surface area of from 1-10000 m², such as from 10-1000 m².

As mentioned above, the placement of the coil inside of the block is very relevant. Firstly, at least a portion of the coil should be placed near the block surface. Preferably, much of the coil has this placement. Therefore, the distance between different coil portions after bents in between should not be too long. According to one embodiment of the present invention, a space may be defined between individual portions of the cooling coil positioned at the same or substantially the same vertical level, and wherein said space is in the range of from 0.5 to 100 cm, preferably in the range of from 2 to 15 cm. One example is a maximum of 30 cm of the space distance between the cooling coils extending in opposite direction to each other. Such a placement of the coil makes it possible to insert as much coil as possible into a limited surface of the block.

According to one specific embodiment, all individual portions of the cooling coil have the same or substantially the same length. This is shown in FIG. 2.

It should be noted that the block according to the present invention may comprise one coil or several separate coils, such as two separate coils. According to one embodiment, the block therefore comprises at least two separate cooling coils.

According to another embodiment, said at least one individual portion of the cooling coil(s) extends adjacent said upper side essentially in a first direction, and wherein the cooling coil thereafter is bent essentially in a plane parallel to the upper side, and thereafter extends adjacent said upper side, forming another individual portion of the cooling coil, in a second direction which is essentially opposite to said first direction. This appearance may be valid both if only one cooling coil is comprised in the block (see FIG. 2), but also if e.g. two separate coils are placed inside of the block. This placement of the coil facilitates inserting as much coil as possible into a limited volume of the block.

Further, a first portion of the cooling coil extends adjacent said underside essentially in a first direction, and wherein the cooling coil thereafter is bent essentially in a plane parallel to the underside, thereafter extends adjacent said underside in a second direction, forming another individual portion of the cooling coil, said direction being essentially opposite to said first direction, after which the cooling coil is bent in a vertical direction, and after which a second part of the cooling coil extends adjacent said upper side. This placement of a first part of the coil leads to an additional cooling effect since the block is placed directly onto the ground.

In one embodiment, all portions and bents of the cooling coil which extend most adjacent said upper side are located a maximum of 3 cm, in the vertical direction, from the upper side, which gives an as efficient cooling as possible even during suboptimal conditions. According to yet another embodiment, all portions and bents of the cooling coil(s) are located a maximum of 30 cm, in the vertical direction, from the upper side. According to a further embodiment, all portions and bents of the cooling coil(s) are located a maximum of 10 cm, in the vertical direction, from the upper side.

Further, the upper side of the block may be an essentially flat surface or a surface having essentially flat protrusions, which facilitates relatively simple manufacturing of the block.

Further, the underside may be an essentially flat surface or a surface having a centrally arranged recess in the vertical direction towards said upper side, which also facilitates relatively simple manufacturing of the block.

In one embodiment, the cooling unit is made of a material comprising a rubber material, a polymeric material, or a mixture thereof. These materials may be used during cooling and are flexible enough such that they can be bent to a meandering shape.

In an alternate embodiment, the cooling coil has a maximum inner diameter of 4 mm and a maximum length of 50 m, which dimensions are suitable for the intended purpose.

According to one embodiment, the porous material comprises concrete (cement), brick, a composite material, or a mixture thereof. These materials are weather resistant which is a must since the invention is intended for outdoor use. Concrete possible to produce today may be a very interesting material to use in the blocks as thermally heavy material may be preferred according to the present invention. Moreover, a porous material managing to store and transport vapour and liquid is preferred according to the present invention. It should also be mentioned that some material may be interesting to finish before being used. For example, a concrete having an acid treated surface may be preferred.

According to a further embodiment, the media intended to be cooled is water, which is a natural and cheap resource.

Said object is achieved, according to a further aspect of the invention, by supplying a cooling system comprising multiple cooling units according to the above, wherein the cooling coil of each cooling unit is connected to at least the cooling coil of another cooling unit. Such a connection of several cooling units increases the total possible cooling.

According to a further aspect of the invention, a cooling unit or a cooling system according to the above is used together with a media intended to be cooled and which flows through said cooling coil in order to generate cooling, such as comfort cooling. It is however important to realise that the cooling unit according to the present invention may be used for other purposes, such as e.g. cooling machinery. Further, the invention may be used in order to generate heat instead of cooling, which is discussed more in detail below.

According to the present invention, there is also disclosed the use of a cooling unit. According to one embodiment, the cooling unit is used together with a media which flows through said cooling coil and is intended to be cooled, in order to generate cooling. One such example is for the use of the cooling unit for the generation of comfort cooling. According to one specific embodiment, the applied flow of the media is from 0.1 to 4.0 m/s. Inter alia the applied media flow, also together with the coil inner diameter, coil length and type of media, gives the possible conversion rate of the media, which is discussed in more detail below. According to the present invention, the extreme value of the lowest conversion rate, i.e. for the application of a water flow of 0.1 m/s in a coil having a inner diameter of 12 mm and a length of 100 m, the conversion rate is as low as about 4 times/h. Below this conversion rate, the possible cooling effect obtained is very low, and therefore it is not of interest to use a lower conversion rate.

Also a too high conversion rate may be undesirable, and the inventor has found that a conversion rate above 600 times/h should not be used. As discussed in more detail below, for instance a conversion rate above 10 times/h, for instance above 50 times/h is preferred. According to one specific embodiment, the applied flow of the media is therefore from 0.4 to 2.0 m/s.

In relation to the possible applications of the cooling unit according to the present invention, it should also be mentioned that the cooling unit modules may be different in their interfaces depending what climate they are intended to be used. This is natural as in different climates and weathers, the cooling unit and block thereof may have different appearance to find best use.

Moreover, the cooling unit and block thereof may be arranged in different ways, e.g. together with other cooling unit modules in systems. Also each cooling unit may be arranged with additional means for special effects. For instance, an air gap may be arranged on the outside of the block. Such an air gap may be contained by a glass plate, steel panel or slab of wood, the later not to recommend in view of possible moisture problems. This is further explained below in relation to FIG. 6.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail below, with reference to the accompanying drawings which, by way of example, show a currently preferred embodiment of the invention.

FIG. 1 shows a perspective view of a cooling unit according to an embodiment of the present invention.

FIG. 2 shows a perspective view of a cooling unit according to an embodiment of the present invention, comprising multiple cooling coils.

FIG. 3 is a sectional view of a cooling unit according to a further embodiment of the present invention.

FIG. 4 is a chart showing a temperature test which was executed for a dry and a somewhat moisture saturated material, respectively.

FIG. 5 is a chart showing a temperature test where the influence of convection on a material surface is evaluated.

FIG. 6 shows a perspective view of a cooling unit according to an embodiment of the present invention, intended for a comfort cooling application, where an air gap is provided for the cooling unit.

DETAILED DESCRIPTION

The present invention, as shown in FIG. 1, relates to a cooling unit 1 comprising a block 2 which may be cube shaped or have any other polyhedron shape. The block 2 has four side surfaces and one upper side 3 and one underside 4, and is made of a porous material. The underside 4 of the block is suitably located directly onto the ground, i.e. outdoors. The ground is shown as a darker block section in FIG. 1. Since the block 2 is made of a porous material, there will be moisture in the pores of the block, e.g. due to rain or moisture being absorbed from the underlying ground, but also from moisture in the surrounding air.

The block 2 comprises a cooling coil 5 which is led into the block 2 and which extends there through, and the cooling coil 5 comprises a media which is intended to be cooled. A first individual portion of the cooling coil 5 extends adjacent the underside 4 of the block and essentially in a first direction, the cooling coil 5 is thereafter bent essentially in a plane parallel to said underside 4, and thereafter extends in another individual portion adjacent said underside 4 in a second direction which is essentially opposite to said first direction. Thereafter, the cooling coil 5 is bent in a vertical direction in a plane parallel to one of the side surfaces of the block. Thereafter, a second part of the cooling coil 5 extends adjacent the upper side of the block 2, essentially in a first direction, which is essentially parallel to the upper side 3 of the block, is thereafter bent essentially in a plane parallel to the upper side 3. Thereafter, the coil 5 extends adjacent the upper side 3 in a second direction which is essentially opposite to the first direction, and is thereafter led out of the block 2.

Generally, concerning the present invention, it is important to realise that the lower part of the cooling coil could be located however far down as desired, i.e. it doesn't have to be located at a specific location in relation to the part of the cooling coil which is located close to the upper side (surface) 3 of the block.

A warm media is pumped into the first part of the cooling coil 5, i.e. the part which is located adjacent the underside 4 of the block and hence also the ground. By a warm media is hereby meant a media which has a temperature which is higher than the temperature which is desired to reach in the media which is pumped out of the block 2. The warm media is, at this point, cooled by the cold in the ground. Hence, the media is cooled as it reaches the second part of the cooling coil 5, compared to when the media was pumped into the coil 5. The second part of the cooling coil 5 is, as previously mentioned, located adjacent the upper side 3 of the block 2.

Since the vapour pressure is higher at the underside 4 of the block 2, the moisture will be pressed upwards towards the upper side 3 of the block. Since the upper side 3 of the block 2 is exposed to solar radiation and/or wind, at least a part of the moisture which is collected in the upper part of the block 2 evaporates. This change of state, from a liquid state to a gaseous state, requires a supply of energy. The energy is collected from the media in the second part of the cooling coil 5, hence cooling the media. For this reason, the second part of the cooling coil 5, i.e. the part which extends adjacent the upper side of the block 2, should not be located more than a maximum of 3 cm, preferably 1-2 cm, vertically inwards into the block 2 as seen from the upper side 3. This second part of the cooling coil 5 may however be located as far as 10 cm from the surface, depending on the climate in question and which material the block 2 is made of.

Further, the direction of the water flow (the media intended to be cooled) depends on application and climate. It is important to realise that the block 2 also may be used as a heat storage, e.g. during cold nights or winter days. Even if the present invention mainly is oriented towards functioning as a cooling unit 1, this device may also function as heat storage if the conditions are right. This obviously also depends on how the system is to be used and how it is to be regulated, such as through flow and specific application, etc. E.g., the cooling unit 1 may function differently during winter since melting of ice/snow may provide the cooling effect instead of the cooling being executed directly through evaporation. Further, the device according to the present invention works very well when exchanging high temperatures, such as e.g. during cooling of machinery.

FIG. 2 shows the location of the cooling coil 5 in the block 2 more in detail. A part of the cooling coil 5 is, as shown, located in one plane, i.e. the first and second parts of the cooling coil 5 are located in separate planes. These planes refer to planes which are parallel to the upper side 3 and the underside 4, respectively. The cooling coil 5 in one plane is arranged such that the parts of the cooling coil 5 which extend in opposite directions are located a maximum of 30 cm from each other in this case. In other words, a part of the coil 5 extends essentially in a first direction, is thereafter bent and thereafter extends in a second direction which is essentially opposite to the first direction, like a serpentine. Both first and second parts of the cooling coil 5 are shaped in this way, in separate planes. The first and second parts of the cooling coil 5 are connected through an essentially vertically directed part of the cooling coil which extends in a direction from adjacent the underside of the block, i.e. the first part of the coil 5, up towards the upper side of the block, i.e. the second part of the coil 5.

It is important to realise that a section, such as that shown in FIG. 2, with e.g. some twenty coils can be connected to a central unit, in other words to a larger system. Several or all of the different block sections cooperate in the central unit.

The upper side 3 of the block 2 is shaped as an essentially planar surface or a surface which has essentially planar protrusions, like a surface with essentially square, protruding teeth. The second part of the cooling coil 5 is led in these so called teeth, i.e. the part of the coil which is to be adjacent the upper side 3 of the block 2. A completely flat surface is desirable for manufacturing reasons, however, a surface having protrusions may be advantageous under certain circumstances, such as when a larger total surface is desired. The shape of the upper side 3 of the block 2 may be varied in other ways, e.g. through coloration. A black surface is, e.g., more suitable than a white since a white surface reflects the light while a black surface absorbs the light, i.e. the black surface is warmer. The warmer the surface, the more heat penetrates into the block and the more efficient the evaporation becomes.

The underside 4 of the block 2 is shaped as either an essentially flat surface or a surface with a central recess 6 arranged in the vertical direction towards said upper side 3, i.e. like an upside-down bucket. Such a recess 6 is shown in FIG. 3. One advantage with such a cavity or recess 6 is that a low pressure may be applied to the cavity 6, which results in that the ability to absorb water molecules changes, which in turn may lead to an acceleration of the evaporation process. The size of the recess 6 may be varied depending on the purpose of the recess 6, but the recess 6 should not be larger than that the second part of the cooling coil 5, i.e. the part which is adjacent the upper side 3 of the block 2, fits in an essentially vertical direction into the remaining upper part of the block 2. A completely flat underside 4 is desirable for manufacturing reasons, but an underside 4 with a central recess 6 may be advantageous e.g. when one chooses to amplify the cooling by letting tap water pass through this recess 6.

The cooling coil 5 is suitably made of a material comprising a rubber material, a polymeric material, or a mixture thereof, e.g. EPDM rubber which is resistant and has good properties as concerns heat transfer. A coil made of EPDM rubber also expands somewhat when the media flow is applied. As such, no hollow spaces are formed between the coil and block material. This increases the efficiency of the energy transfer.

The cooling coil 5 preferably has a maximum inner diameter of 4 mm, but absolutely not more than 12 mm. The conversion has to be high such that the difference in temperature between incoming media intended to be cooled in relation to outgoing cooled media is kept as low as possible. The cooling coil 5 should preferably have a maximum length of 60 m in order to avoid that the resistance in the coil 5 is too large. One preferred length range is 30-60 m. In this sense it should be noted that also shorter and longer cooling coils are possible according to the present invention, and one such range being fully possible is from 5 to 100 m. It is advantageous if the block 2 comprises a relatively long cooling coil 5 with a small diameter in order to achieve a cooling effect which is as good as possible.

As briefly discussed above, the conversion level or rate of the media intended to be cooled is an important factor according to the present invention. According to a specific embodiment of the present invention, said at least one cooling coil 5 is dimensioned and arranged within the block 2 such that a conversion of at least 50 times/h is achieved at a flow of media which is less than or equal to 5 l/min, such as a conversion of at least 50 times/h at a flow of media which is less than or equal to 2 l/min, e.g. a conversion of at least 50 times/h at a flow of media which is less than or equal to 1 l/min. Even higher conversions may be achieved according to the present invention, which is shown below by a comparative example.

Starting with two different kinds of cooling coils, one having an inner diameter of 4 mm and the other having an inner diameter of 15 mm. Further, the applied flow is assumed to be 0.95 l/min and the distance between the coils is 15 cm. Such a distance results in about 6 coils/m² as a rough estimate. Further, if the cooling coils are assumed to be 50 m, the conversion for the two different inner diameters is calculated with the given flow, and the media is assumed to be water, a conversion of approximately 137 times/h for a 4 mm inner diameter and a conversion of approximately 10 times/h for a 15 mm inner diameter is achieved. Since the conversion is proportionally dependant on the flow, the flow could of course be increased in order to achieve a corresponding percentage increase of the conversion. Of course, more pumping force is necessary if the flow is increased significantly, which in turn costs energy and hence money. Therefore it is desirable to keep the flow low and still maintain the conversion high.

The inventor has found that, regardless of the dimensions of the cooling coil, a conversion of 50 times/h or higher is desirable. This would, in the examples above, mean that one has to increase the flow 5 times, i.e. to almost 5 l/min in order to achieve this when the inner diameter is 15 mm. This would of course have a cost in increased pumping force. However, as regards an inner diameter of 4 mm, a conversion well above 50 times/h was achieved, and, as should be realised, conversions above 150, above 200, above 250 etc. are possible according to the present invention. Hence, it is a question of dimensions of the cooling coil, how the cooling coil is arranged in the block, which length the cooling coil has, and which flow of media is being used.

Returning to the Figures, in FIG. 4 is shown a chart for temperature tests. The tests were made with porous sponge material as samples with different moisture saturation levels, namely dry, wet and moderate. The base was a concrete slab with a black surface in order to reduce the spreading of radiation which was obtained from the energy source, which was three infrared lamps (100 W) which were placed at a distance of 0,3 m from the samples. As realised, three different tests have been performed, namely one test with a dry material sample and where the thermal element, which measures temperature, is located at the surface (graph 1), one test with a moderately moisture saturated material sample and where the thermal element is located in the surface (graph 2), and finally one test with the same moderately moisture saturated material sample as in graph 2 but where the thermal element is about 2 cm into the material sample (graph 3). As shown in the chart, the temperature is given in ° C. on the y-axis against time in hours (h) on the x-axis. What is seen in the chart is that the moist material sample had a dip in temperature, i.e. where graph 2 bends downwards, which shows that the evaporation which is the basis for the present invention in fact happens, and has a significant meaning. Such a bend isn't seen in the dry material in graph 1. There is also a difference between graph 2 and graph 3, from which the temperature in the material surface is shown in graph 2 while the temperature within the material is shown in graph 3. Hence, graph 3 shows the impact of IR radiation alone, and not of evaporation in the surface. This too can be a basis for proving the effect of locating a cooling coil 5 or a part of a cooling coil 5 close to the surface of a block 2, such as according to the present invention, in order to use the evaporation enthalpy for cooling a media such as water. Graph 2, in relation to 3, shows the importance of locating the cooling coil 5 close to the upper side of the block.

FIG. 5 shows a test corresponding to that of FIG. 4, but in this case only the influence of convection on the present invention is measured. In this case, graph 1 corresponds to room temperature during the test and graph 2 shows the temperature at the surface when this is influenced by convection, i.e. wind, without IR radiation. In this case, the thermal element is located about 1 cm below the surface. As shown in FIG. 5, the temperature drops relatively quickly in the material as the surface is affected by wind. This means that the material is cooled and that this cooling may be used for cooling a media in a cooling coil 5. Also in this case it is important to keep the cooling coil 5 close to the upper side 3 of the block.

FIG. 6 also shows a cooling unit 1 comprising a block 2. The cooling coil(s) 5 are shown in a cross sectional view. Furthermore, there is also provided a protective material 7 which forms an air gap between the block 2 and the protective material 7. The protective material may have different functions. First of all it may be used as a shielding to enhance the appearance of the front, so that this front is not only a concrete wall. Secondly, it may have a protective function, e.g. being made of steel, glass, isolation, etc. When for instance being made of a glass material, the protective material 7 protects against solar incident radiation and instead uses the sun to heat the glass so that convective flows of air occur between the protective material 7 and the block 2. The convection then accelerates the evaporation of liquid on the surface, thus a better cooling effect may be obtained. With a relatively warmer air temperature, the air flow in the gap collects an increased level of moisture from the material, which in turn gives an increased level of evaporation.

The porous material in block 2 may be concrete, brick, a composite material, or a mixture thereof. If the block 2 is made of concrete (cement), it is advantageous if the water cement ratio is at least 0,6. That which is crucial for the choice of material is that the material is weather proof and has pores with a minimum pore size which is larger than the water molecule in vapour phase, such that the water molecules can be transported freely within the block 2. This facilitates both absorption of water into the block 2 and evaporation from the block 2. For the same reason, it is usually advantageous if the pores extend in an essentially vertical direction, even if other solutions are possible. The dimension of the upper side 3 of the block is suitably 10-20 m²/unit, but other dimensions are also conceivable.

The media intended to be cooled is suitably water, since this is a cheap, naturally occurring resource without environmental impact. Other media may be used as well, e.g. in order to achieve a better cooling effect.

Multiple cooling units 1 can be connected to one cooling system, wherein the cooling coil 5 of each cooling unit 1 is at least connected to the cooling coil 5 of another cooling unit 1. The units may, e.g., be connected in series or in parallel. However, the limitation that the total cooling coil should not be more than 50 meters long remains.

A cooling unit 1 or a cooling system is used together with the media which flows in at least one cooling coil 5 in order to generate comfort cooling, but as mentioned there are other possible applications. The unit or the system is used at low temperature differences in order to supply, e.g., comfort cooling to a grocery shop. One example of use is when the unit(s) is/are placed at a parking lot outside the facility which is to be cooled, at the roof of the facility or near decorative water such as fountains since the decorative water may, in this case, interact with the cooling unit 1. The cooling effect is achieved, as previously described, since the media which is pumped through the cooling coil 5 is cooled at least by the evaporation which occurs naturally in a porous block 2 without further supply of energy. The reason that the application of generating comfort cooling is especially mentioned is that only small differences in temperature are achieved. The unit or system shouldn't, e.g., be used for cooling for example refrigerators or freezers, but is most definitely suitable for cooling the indoor temperature of a facility by a couple of degrees.

It is realised that modifications of the above described embodiment of the invention are possible within the scope of the invention, such as defined in the subsequent claims. For example, the block and the coil may be made of any suitable material. Also, the shape of the underside of the block may be adapted to the concerned foundation, e.g. if the block is located at a surface with a large inclination. In the same way, the upper side of the block may be adapted to current conditions, e.g. shadow, such that as much sun and/or wind as possible reaches the upper surface. Further, the block may be made in several different heights, such that the upper side and/or the underside are shaped as steps with different heights. 

1. Cooling unit comprising a block having an upper side and an underside, and at least one cooling coil extending at least partially through the block, in which cooling coil a media is intended to be cooled, characterised by the cooling coil comprising individual portions, each defined as the extension in one direction before a bent of the cooling coil, wherein at least one individual portion of the cooling coil is located a maximum of 10 cm, in the vertical direction, from the upper side, and wherein the inner diameter of the entire cooling coil is in the range of from 3 to 12 mm.
 2. Cooling unit according to claim 1, wherein the block comprises a porous material having a porosity of from 20-98%.
 3. Cooling unit according to claim 1, wherein the length of the cooling coil is in the range of from 5 to 100 m.
 4. Cooling unit according to claim 1, wherein the inner diameter of the entire cooling coil is in the range of from 4 to 8 mm.
 5. Cooling unit according to claim 1, wherein the cooling unit has a surface area of from 10-1000 m².
 6. Cooling unit according to claim 1, wherein a space may be defined between individual portions of the cooling coil positioned at the same or substantially the same vertical level, and wherein said space is in the range of from 0.5 to 100 cm.
 7. Cooling unit according to claim 1, wherein all individual portions of the cooling coil have the same or substantially the same length.
 8. Cooling unit according to claim 1, wherein the block comprises at least two separate cooling coils.
 9. Cooling unit according to claim 1, wherein said at least one individual portion of the cooling coil(s) extends adjacent said upper side essentially in a first direction, and wherein the cooling coil thereafter is bent essentially in a plane parallel to the upper side, and thereafter extends adjacent said upper side, forming another individual portion of the cooling coil, in a second direction which is essentially opposite to said first direction.
 10. Cooling unit according to claim 9, wherein a first portion of the cooling coil extends adjacent said underside essentially in a first direction, and wherein the cooling coil thereafter is bent essentially in a plane parallel to the underside, thereafter extends adjacent said underside in a second direction, forming another individual portion of the cooling coil, said direction being essentially opposite to said first direction, after which the cooling coil is bent in a vertical direction, and after which a second part of the cooling coil extends adjacent said upper side.
 11. Cooling unit according to claim 1, wherein all portions and bents of the cooling coil(s) are located a maximum of 30 cm, in the vertical direction, from the upper side.
 12. Cooling unit according to claim 1, wherein all portions and bents of the cooling coil(s) are located a maximum of 10 cm, in the vertical direction, from the upper side.
 13. Cooling unit according to claim 1, wherein all portions and bents of the cooling coil which extend most adjacent said upper side are located a maximum of 3 cm, in the vertical direction, from the upper side.
 14. Cooling unit according to claim 1, wherein said upper side is an essentially flat surface or a surface having essentially flat protrusions.
 15. Cooling unit according to claim 1, wherein said underside is an essentially flat surface or a surface having a centrally arranged recess in the vertical direction towards said upper side.
 16. Cooling unit according to claim 1, wherein said cooling unit is made of a material comprising a rubber material, a polymeric material, or a mixture thereof.
 17. Cooling unit according to claim 1, wherein the block comprises a porous material comprising concrete, brick, a composite material, or a mixture thereof.
 18. Cooling system comprising multiple cooling units according to claim 1, wherein the cooling coil of each cooling unit is connected to at least the cooling coil of another cooling unit.
 19. Method of using a cooling unit according to claim 1 or a cooling system according to claim 18, together with a media which flows through said cooling coil and is intended to be cooled, in order to generate cooling.
 20. Method according to claim 19, wherein the applied flow of the media is from 0.1 to 4.0 m/s.
 21. Method according to claim 20, wherein the applied flow of the media is from 0.4 to 2.0 m/s.
 22. Method according to claim 19, wherein the media is water. 